For convenience, the Engine and Chassis numbers have
been split into various sections. For ease of use, I've kept most engine capacities on one page,
however this does mean that

Some pages will be slow to load

I figure a slow page is preferable to lots of little ones so please be
patient as the results will be worthwhile.

These pages are now available in PDF format

Up until the introduction of the Mono-Shock models, engine and chassis
numbers were matched, however, the introduction of the K Series machines
heralded the demise of this simple means of identification and currently the
engine and frame numbers bear no relation to each other over the whole model
range. One advantage of the change is that with the later models, it is now
possible to tell the year of manufacture of the engine.

As I understand it - no guarantees here!!! A years model production begins
after the workers return from the main summer works shut down in the
previous year - I believe production starts around the beginning of
September for the next years model production.

All Monoshock R Series engine numbers will look something like this:
08/87/0128 - the first two digits refer to the
week of production, the second pair indicate 1987 as the production year and
the final four digits represent the number in that weeks production.

A K Series engine number will look something like this:
104EA 1799 2032 - the first two digits refer to
the engine capacity (1000cc); the third digit shows the number of cylinders;
EA is some reference to a Federal Emission Code; sixth & seventh digits are
the production week number (week 17); eighth & ninth digits are the year of
manufacture (1999); the final four digits are the production number on that
weeks production.

Unleaded Fuel

R80 (UK) unleaded from chassis number 6440512
(1985)

R80RT (UK) unleaded from chassis number 6470498
(1985)

R80G/S (UK) unleaded from chassis number 6283306
(1985)

All unleaded head have a blue paint spot near the bottom
head nut.

I have no information regarding the exact time that the other R Series machines
were changed to unleaded. ALL twin shock machines were designed for leaded
fuel and MOST monoshock machines are built for unleaded fuel.

Early K Series machines were designed for leaded fuel - this was changed
sometime early in 1985 from the Chassis Numbers listed below.

K100 (UK) unleaded fuel from chassis number 0 007 291

K100RS (UK) unleaded fuel from chassis number 0 081 107

K100RT (UK) unleaded fuel from chassis number 0 024 999

I have no information on the relevant chassis numbers for US models - if
anyone has this information, please let me know so it can be included here.

All information I
currently have has now been transcribed - there is still much more
to come as and when I can get the information although this may not
yet be available for current models. If you have information that is
not included, please let me have a copy to share with all